Lift mechanism for extending a horizontal support



May 8, 1956 LIFT MECHANISM FOR EXTENDING A HORIZONTAL SUPPORT Filed Nov.24, 1952 W. C. MCMAHAN 2 Sheets-Sheet l 75e C. MoMA/4M IN V EN TOR.

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May 8, 1956 W C;- MCMAHAN 2,744,805

LIFT MECHANISM FOR EXTENDING A HORIZONTAL SUPPORT Filed NOV. 24, 1952 2Sheets-Shea? 2 "431.752 C. McMA/MM INVENTOR.

United States vPatent CC man -Mt 1892.2

' VLm'r MECHANISM 'Fon EXTENDHSTG A f HORIZONTAL SUPPORT This inventionrelates to a liftrmechanism, such as is adapted to be incorporated indesks for mounting 4typewriters, or lin kitchen cabinets forzvmountingappliances and tliellike. j f :Such-,liftscommonly employ a shelf thatmay be vrnanua'lly.v moved from an inactive position below the'top ofthe vdesk or cabinet to an active position projecting laterally ofthedesk or cabinet, and adjacent the top. One suchmechanism is disclosedand claimed in a prior" ap# plication inthe name of Walter C. McMahan,Serial No. 212,535, filed` February 24, 1951, now Patent, No.' 2,676,-077', issued April 20, 1954, and entitled` TypewriterLift Mechanism, ofwhich the present application ,is a continuation-in-part.

It isl anobject of the present invention to improve, in general, suchlift mechanisms.

Y kIt is another object of this invention to` provide asimple-.mechanism of this character whereby the plat- 2 anddash lines inFig.-2. The platform may serve to support any `other device as, forexample, a typewriter or the like beneath a desk top.

.The platform 10 is suspended by the aid ofparallelogram'linkagevcomprising four similararmsor links 12, 13, 14,'and l15.I The lower ends of each of the links are mounted at oppositesides 16 and 17 of the platform 10. For this purpose, a metal strip 18is secured to the side 16 by the aid of wood or other appropriate screws19 and 20. The strip 18 projects rearwardly beyond the rear surface 21of-the platform 10. The end of the link 12 is pivotally connected to theinside of the rearwardly projecting end 22 of the strip 18, as by theaidof a suitable pin 23. The end of the link 13 is` similarly pivotallymounted to .the outside of the .strip 18 by the. aid of-a pin 24. Thelinks 14 and 15 are similarly pivotally connected lto the 'platform 10at the other side 17 thereof. For this purpose, a' strip or plate 25 isprovided.

The upper ends of the links 12, 13, 14, and 15 are mounted on a rigidstationary frame ystructure comprisin gba'rs 26 'and 27 that are, inturn, secured to the cabinet 2S in a manner to be hereinafter more fullydescribed. For pivotally mounting the upper ends of the links 12 and-13to the bar 26,=pins 29 and 30 are provided.' Sim'- ilarly, pins 31 and32 pivotally mount the Yupper ends of links 14`and 15 to the bar 27. Abrace 33 joins the form may be elevated to a position in which it ismost accessible. I t is still another object of this invention to makeit possible to fit the mechanism into cabinets of slightly differentsize. For this purpose, the supporting structure incorporates anadjustable element.

It lis stillanother object of this invention to provide a support ofthis character, which, whenwelevated, is positivelygand automaticallyrestrained against inadvertent movement, all in animproved andsimplified manner, andin which thefrestraint is easily manuallyyreleased.4 This yinvention possesses manyother advantages,and has otherobjects which may be made more clearlyapparent from a consideration of,onelembodiment ofthe invention.A For this purpose, thereis shown a formin 4the .drawings accompanying and lforming part kof the presentspecification. The form willnow be described in detail, illustrating thegeneral principles of the invention; but itis to be understood that thisdetailed descrip- .tion is not to be taken in a:limiting sense, since.the scope of t h,is invention .is best defined by the appendedclaims.

; =Referring tothe drawings: Figure Jl is a top view Acfa deviceincorporating the presentjinvention, the-cabinet ,in which the device isiaccommodatedzbeing,shownin section; j

Fig. A2 is..,a vertical elevation of the apparatus -in the loweredposition as illustrated-in Fig. 1, the cabinet also being showninsection; j a n Fig. 3 is a view similar to Fig. 2, the apparatusv'beingshown in raised position, the'cabinet in whichy the device isaccommodated being illustratedfas a fragmentary secl Fig.. 4 is an,enlarged fragmentary viewl of theglocking mechanism in the position ofFig. 3, the dotiand dash linesl illustrating the manner in which themechanism is released; and 1 FignS, is a pictorial view ofthe complete'apparatus; 'illust'rated in lowered position. f -zA platform-10, of anysuitable form, forms the base upon which-an appliance, or the like, mayfrest. An applianc'efsuch as an electric mixer 11, is illustrated in dotparallel bars 26 and 27 and cooperates therewith to form a rigidconstruction. The ends of 'the `brace 'are secured, as by welding, totheforward portion of the bars 26 and 27. l j

The spacing between the pins 23 and 24, mounting the lower ends of thelinks 12 and 13, substantially precisely corresponds to the spacingbetween the pins 29 and 30 mounting lthe upper ends .of the links 12 and13 to the bar 26. Similarly, the spacing between the pinsmountingjthe'lower ends of the links 14 and 15 corresponds to thespacingbetween the'pins 31 and 32vmounting the upper ends of Ithe links14 and 15I to the frame member 27. The axes of the pins 29, 30, 31, and32 mounting the links 12, 13,14, and 15 to the'frame 26, 27, andplatform 10 respectively extend parallel to each other end. By virtue ofthese arrangements, a swinging parallelogram suspension for the platform10 is provided, in which the platform 10 is optionally positionable inspaced parallel planes.v vThe platform 10 remainsv horizontal for allpositions thereof upon proper initial orientation of the device. i Forvmounting the frame members 26 and 27 within kthe cabinet 2 8,supporting members 34 and 35 are provided'. The supporting members v34and 35y arerespectively kdisposed/immediately below the frame members 26and 27. The frame members 26 and 27 andthe supporting members34 and 35are respectively secured together, as'by the aid of appropriate welds 36(Figs.v 4 and'5)'. The end`s'37` and`38 of the member 34 `are offset ina direction outwardly of the frame member A26 (see, also, Fig.Y 1). l Anappropriate screw 39 passes throughf an appropriate aperture in theoffset end 37 to secure that end 'of the supporting member toa cleat 99immediately below the cabinet top. The other offset portion 38 of the'supporting member 36 adjustably mounts a reversible bracket41 (Figs. 1and 5). The bracket 41 has a ange 4 2y that may extend inwardly oroutwardly, .depending upon the manner in which the structure is bestadapted to be secured to the cabinet. In the present instance, thetlange42 abuts a vertical stud or brace 43 in thel rear corner of thecabinet 28.'v

The bracket 41 is also adjustable longitudinally of the supportingmember 34 so that the supporting member 34 can conform rwithin limits tothe size requirements of thecabinet in which it is installed. For thispurpose, and

to provide for a reversal of the bracket 41, a strap 44 (see, also, Fig.5) is carried by the bracket 41 and defines therewith a space receivingthe offset end 38 and the bracket 41. The strap 44 may have its endsextending over the edges ofv the bracket 41 and welded thereto.Accordingly, the mounting bracket 41 is slidahly movable longitudinallyof the offset end 38 and confined for such movement by the aid of themember 44. Furthermore, the bracket can be reversed in order to reorientthe ange 42.

The left-hand supporting member 35 cooperates with the frame member 27in a precisely symmetrical manner. This supporting member 35 has offsetends 45 and 46, the rearward olset portion 46 adjustably mounting abracket 47 similar to bracket 41. Appropriate screws 48, 49, and 50,together with the screw 39, properly mount the structure in the cabinetrecess.

The platform is swingable from the lowered position illustrated in Fig.2 to the raised position illustrated in Fig. 3, the links 12, 13, 14,and rotating about their upper pivotal mountings provided by pins 29,30, 31, and 32.

The configuration of each of the links 12, 13, 14, 15 is such that inthe elevated position of Fig. 3, maximum height of the platform 10 canbe achieved. Thus, in this position, those ends 12a, 13a, 14a, 15a ofthe links attached to platform 10 all extend slightly above the level ofthose ends 12b, 13b, 14b, 15b of the links attached to the frame members26 and 27. The platform 10 thus lies close to the top surface of thecabinet 28.

To permit this function, the links 12, 13, 14, 15 are of a particularconfiguration, wherein they extend generally on one side of a straightline joining the pivotal mountings 23-29, 24-30, etc. of each link. Inthe present instance, the links are of angled configuration, the ends12a, 12b of link 12, for instance, forming an obtuse angle at an apex12C. Optionally, the links 12, 13, 14, 15 could be in the form of anarc. By virtue of this conguration, there is clearance between the linksand the mechanism supported by the frame members 26. and 27 to permitthe platform 10 to reach the elevated position of Fig. 3.

Provisions are made to permit the ends 12a, 14a of rear llinks 12 and 14to pass the forward links 13 and 15 respectively as these links movefrom the position of Fig. 2 to the yposition of Fig. 3. For thispurpose, the distance between the outer surfaces of ends 12a and 14a issubstantially less than the distance between the inner surfaces of thelinks 13 and 15, so that the inner links 12 and 14 can extend betweenthe outer links 13 and 15 (see Fig. 3).

These relative spacings are obtained because the ends 12a and 14a aremounted inwardly of the strips 18 and 25, while the ends 13a and 15a aremounted exteriorly thereof.

A brace 76 connects the rear links 12 and 14 together and also serve tomaintain a rigid and slightly converging configuration between links 12and 14. This brace 76 is joined as by welding to the respective apicesof the bends of the rear links.

In order to maintain the platform 10 in an elevated position, hook orcatch members 51 and 52 are provided. These catch members extendvertically from braces S3 and 54'. Brace 53 extends substantiallyparallel to the frame member 26 and the strip 18 and joins the links 12and 13 midway of their lengths and above the bends respectively. Thebrace S3 is pivoted to the link 12 by the aid of a pin 55, and ispivoted to the link 13 by the aid of a pin 56. The brace 54 is similarlysecured.

As illustrated in Figs. 3 and 5, and by a comparison between them, thelower portion of the rear link 12 must also cross the brace 53 inreaching the elevated position. In order to permit this, the end 57 ofthe Vbrace that is secured to the rear link 12 is inwardly offset.

The hook or catch 51 is rigidly secured to the brace 53 in a suitablemanner. Upon the platform 10 being moved to the elevated position, thecatch 51 is moved into latching relationship with the lock bar 58. Thislock bar 58 is carried by the frame members 26 and 27. The ends of thebar 58 are mounted in parallel elongate slots 59 and 60 in the ends ofthe frame members 26 and 27 respectively. Collars 61 and 62 prevent thebar 58 from moving longitudinally. The bar 58 is thus movable in adirection transverse to its axis and in a plane extending longitudinallyof both of frame members 26 and 27.

A U-shaped handle 63 is mounted upon the lock bar 58 for manipulationthereof. For this purpose, the bar 58 extends through apertures in thearms of the handle respectively. Tension springs 64 and 65 are securedto the ends of the handle and the brace 33 as by suitable aperturesreceiving end turns of the springs. These springs 64, 65, as viewed inFig. 4, normally urge the handle and lock bar 58 toward the right intheir guiding slots 59 and 60. As the platform 10 reaches the elevated.position illustrated in Fig. 3, the latch or catch 51 engages the lockbar 58 near its end to move the lock bar against the force of thesprings 64 and 65 and toward the left, as viewed in Fig. 4. For thispurpose, the catch 51 has an upper cam surface 66. A slot 67 in thecatch 51 receives the lock bar 58 upon further movement of the catch 51in an upward direction. This latching recess 67 adjoins the cam surface66. The lock bar 58 is urged into the recess 67 by the operation of thetension springs 64 and 65 after the cam surface 66 is no longereffective.

Downward movement of the platform 10 is then prevented by engagement ofthe lock bar 58 with the hook 51. Further upward movement from theelevated position is similarly limited. The latch 52 operates in anentirely symmetrical manner and simultaneously with the catch 51. Thecatches 51 and 52 pass inwardly of the olfset ends 37 and 45 of thesupporting members 34 and 35 respectively upon the platform reaching theelevated position.

In order to release the mechanism so that it may be moved to the loweredposition, the handle 63 is moved outwardly. This handle is convenientlylocated, as shown most clearly in Fig. l, and is readily available formanipulation by the user. To release the mechanism, the handle 63 ismoved outwardly in the direction of the arrow 68, illustrated in Fig. 4,to the dotted line position therein illustrated. The lock bary 58,mounting the handle 63, is similarly moved outwardly to the dotted lineposition, where it is freed from engagement with the upper Wall of theslot 67. Accordingly, the catches 51 and 52 can pass downwardly withrespect to the latch member 58, and theV entire mechanism can beretracted.

In order to maintain stable positioning of the mechanism and to assistlin lowering and raising the platform 10, an eccentric springconstructionv is provided. For this purpose, heavytension springs 69 and70 are provided. These springs 69, 70 have ends secured to a U-shapedbracket 71 of ytwisted'configuration. This bracket 71 also cooperateswith the brace 33 to maintain a rigid configuration with the framemembers 26 and. 27. The other ends of the springs 69 and 70 are securedto the brace 33. Conveniently, the springs 69= and 70 may pass throughthose apertures 72 and 73 of the brace 33 that also mount the tensionsprings 64 and 65 respectively.

The arms 74 and 75 of the U-shaped bracket are secured to the rear links12 and 14 respectively at a place spaced from, but close to, the pivotedpins 29 and 31. Accordingly, the bracket 71` is arcuately movable alongwith the links 12 and 14. V

In the position illustrated in Fig. 2, the spring 69, for instance,extends on one side of the pivot pin 29 about which one end of thespring 69 is arcuately movable.v In this position, the spring 69 urgesthe construction in a counterclockwise direction. The spring 70 operatessimilarly. This corresponds to maintaining the apparatus in theloweredposition. As the device is rotated,however,

the place of attachment of the ends of the springs 69 and 70 moves withrespect to the pivot pin 29 and the place of attachment of the otherends of the springs 69 and 70. After an initial movement correspondingto further tensioning of the springs 69 and 70, the springs 69 and 70pass the pivot pins 29 and 31 respectively and then extend on theopposite side of the pins 29 and 31 about which the ends of the springs69 and 70 are arcuately movable. Accordingly, the springs 69 and 70 nowurge the mechanism in a clockwise direction corresponding to elevatedposition of the mechanism. The tension springs 69 and 70 thus assist inmoving the mechanism and also to maintain it in stable position.

The inventor claims:

l. In a lift mechanism: a pair of frame members; a pair of rear linkspivoted on a common axis by said frame members respectively; a pair offorward links pivoted on a common axis spaced from said first axis andby said frame members respectively; a support; means pivotallyconnecting the links to the support; those ends of the links attached tothe support being forwardly inclined so that when said support iselevated to the level approximating that of said frame members,clearance is provided between said rear links and the forward ends ofsaid frame members; said frame members having longitudinally extendingslots at their forward ends; a latch bar extending between said framemembers and guidingly received in said slots; a handle carried by thebar substantially centrally thereof; resilient means urging said barrearwardly of said frame members; and a hook member engaging said barupon movement of said support to an elevated position, said hook memberbeing carried by said links.

2. In a lift mechanism: a pair of frame members; a pair of rear linkspivoted on a common axis by said frame members respectively; a pair offorward links pivoted on a common axis spaced from said first axis andby said frame members respectively; a support; means pivotallyconnecting the links to the support; those ends of the links attached tothe support being forwardly inclined so that when said support iselevated to the level approximating that of said frame members,clearance is provided between said rear links and the forward ends ofsaid frame members; said frame members having longitudinally extendingslots at their forward ends; a latch bar extending between said framemembers and guidingly received in said slots; a handle having anaperture through which said bar extends; resilient means engaging an endof the handle for urging said bar rearwardly of said frame members andfor angularly orienting said handle; and a hook member engaging said barupon movement of said support to an elevated position, said hook memberbeing carried by said links.

3. In a lift mechanism a: support; a pair of strips adapted to besecured to opposite sides of the support; said strips being adapted toproject rearwardly beyond said support; a rst pair of arms pivotallysecured at one end to the rearwardly projecting portions of said stripsrespectively; a second pair of arms pivotally secured at one end to saidstrips respectively and forward of said rearwardly projecting portions;said arms all being of similar angled configuration between their ends;a pair of frame members pivotally securing the other ends of said arms;said arms providing a parallelogram suspension for said support formovement of said support from a lowered position to an elevated positionwith respect to said frame members; a bar extending between said framemembers, said frame members having slots guidingly receiving the ends ofsaid bar for translation of said bar in a direction longitudinally ofsaid frame members; and at pair of hook members carried by said arms andengageable with the ends of said bar upon movement of said arms toelevate said support; the angled configuration of said first pair ofarms providing clearance between said arms and said bar.

4. In a lift mechanism: a support; a pair of parallel ner sides of saidstrips; a second pair of arms, each arm being pivotally secured at oneend to said strips respectively and forward of said rearwardlyprojecting portions, said pivotally secured ends of said second pair ofarms being disposed on the outside of said strips; a pair ofsubstantially parallel frame members, one of said frame memberspivotally securing the other end of one of said first pair of arms andthe other end of one of said second pair of arms on one side of said oneframe member, the other of said frame members pivotally securing theother end of the other of said first pair lof arms and the other end ofthe other of said second pair of arms on one side of said other framemember; said first pair of arms having anangled configuration; said armsproviding a parallelogram suspension for said support for movement ofsaid support from a lowered position to an elevated position withrespect to said frame members; and a releasable latch for holding saidsupport in an elevated position, and carried by said frame members, theconfiguration of said first pair of arms providing clearance betweensaid first pair of arms and said releasable latch, and the mounting ofsaid pairs of arms on said strips providing clearance between the firstpair of arms and the second pair of arms,

5. In a lift mechanism: a pair of parallel spaced frame ogram suspensionfor a platform or the like; a pair of supporting members extending injuxtaposed relationship with respect to said frame elementsrespectively, each of said pair of supporting members having an offsetend; a pair of bracket members for said ends respectively having aflange for attachment to a cabinet or the like; and a pair of loops forremovably and slidably mounting said brackets with respect to saidoffset ends respectively, said brackets being reversible on said endsfor reorienting said anges.

6. In a lift mechanism a: pair of substantially parallel frame members,each of said frame members having a slot at one end thereof forreceiving a latch bar; a latch bar having ends accommodated in saidslots and guided for translation in a direction substantiallylongitudinally thereof by said slots; resilient means urging said bar inone direction in said slots; a rst pair of arms pivotally mounted at oneend on said frame members respectively, said rst pair of arms being ofangled configuration; a second pair of arms pivotally mounted at one endon said frame members respectively and spaced from said rst pair ofarms; a platform pivotally mounting the other ends of said arms, saidarms providing a parallelogram suspension for said platform; thedistance between the other ends of said first pair of arms being lessthan the distance between the other ends of said other pair of arms; anda catch carried by said arms for engagement with said bar upon movementof said platform to an elevated position.

References Cited in the le of this patent UNITED STATES PATENTS1,035,664 Vaaler Aug. 13, 1912 1,606,975 Tobey Nov. 16, 1926 2,322,648Lundstrom June 22, 1943 2,428,211 Fox Sept. 30, 1947 2,561,505 Fox July24, 1951 2,585,566 Lundstrom Feb. 12, 1952 2,676,077 McMahan Apr. 20,1954 FOREIGN PATENTS 99,489 Switzerland June 1, 1923

